In many electronic systems, some critical components of the system such as voltage references, and regulated voltages and currents, may require some time to stabilize. To avoid improper functioning of these systems, these components must stabilize to a known power state before beginning the normal operation. Power-on Reset (POR) circuits are typically used to initialize stable power states, ensuring that booting is accomplished safely. POR circuits force the system into a reset state upon power supply activation and maintain the system in that state until power is stabilized, as indicated by a parameter such as a voltage reference. It is typically also of value to de-assert the reset condition as early as is safe to do so.
Many different electronic designs have been attempted to improve the performance of the POR circuits. However, significant improvements are still needed in the following areas of POR performance: detecting stable operation of various system components which could power-up in a variety of ways depending upon process and temperature variations and upon varying power-up ramp times of the supply, recognizing false appearance of requirements for de-assertion of reset, and avoiding excess time beyond the necessary conditions to improve system performance.